1. Field of the Invention
The present invention relates to an ion measuring system, and in particular relates to a multi-electrode measuring system which is able apply for biomedicine, chemistry related fields, etc.
2. Description of the Related Art
The ion sensitive field effect transistor (ISFET) was first invented by P. Bergveld in 1970, and the ISFET is based on a metal-oxide-semiconductor field effect transistor (MOSFET). Moreover, the gate of the MOSFET was replaced by a sensing membrane and electrolyte. A sensing membrane and H+ and OH− in a sample solution results in an adsorption-binding effect to make the potential on the surface of an electrode change, thus obtaining the ion concentration of a sample solution.
In 1983, J. Van der Spiegel et al developed an extended gate chemical sensitive field effect transistor, which used a plane array structure, including four sensing parts deposited of different materials such as IrOx, LaF3, AgCl and Ag2S to from the sensing thin films for detecting four kinds of ions, H+, F−, Cl− and Ag+, (J. Van der Spiegel, I. Lauks, P. Chan D. Babic, 1983, “The extended gate chemical sensitive field effect transistor as multi-species microprobe”, Sensors and Actuators B, Vol. 4, pp. 291-298).
Taiwan Patent No. I236533, disclose a biochemical sensing method and the sensing device thereof. A current/voltage converting circuit is able to convert current signals into analog voltage signals; and the analog voltage signals may be converted into digital voltage signals by an analog/digital converter; finally an electronic device is used to receive and analyze the digital voltage signals and an amount of a specific compound is determined by the analyzing step.
U.S. Pat. No. 7,348,783 disclose a multi-functional pH meter and the fabrication thereof. The pH meter provides an immediate display of the measurement result and a saving function which is beneficial for development of a portable detecting device. In addition, the multi-functional pH meter has data communication functionality with a computer, drift and hysteresis software calibration is also provided.